Platelet-Rich Plasma for Patellar Tendinopathy: A randomized controlled trial correlating clinical outcomes and quantitative imaging

Abstract Background Patellar tendinopathy (PT) is a common overuse injury in active individuals, often with incomplete recovery. Recently, platelet-rich plasma (PRP) treatment has shown promising results. Traditional qualitative markers are not reliable indicators of treatment response. Advanced quantitative imaging, such as Ultrashort-TE (UTE) MRI and ultrasound (US) shear-wave elastography (SWE) may be valuable adjuncts. Purpose To investigate the clinical outcomes and quantitative imaging changes in adults with symptomatic patellar tendinopathy treated with PRP, needle tenotomy (NT) or sham injection (SH). Materials and Methods Single-blinded prospective randomized controlled trial from April 2017 until July 2022 with three parallel interventions in athletes with symptomatic PT: PRP, NT and SH. VAS pain, VISA-P function, conventional US, shear wave speed (SWS), UTE T2* relaxation time (T2*single) and T2* fraction of fast-relaxing macromolecular-bound water (FF) were acquired at 0, 16 and 52-weeks. Longitudinal analyses were used to compare intra- and inter-group differences over time. Correlations were assessed by Pearson’s correlation coefficient. Results 29 subjects (mean age, 26.1±5.3 years; 82.8% men) were randomized. At 52-weeks all groups demonstrated a significant improvement in pain, though most pronounced within the PRP group (ΔVAS=-5.9, 95% confidence interval (CI) -7.8, -3.9, p.001). SWS increased significantly only in the PRP group (Δ+2.3, 0.8, 3.9, p=.003). Change in SWS was moderately correlated with change in pain across all groups (r=-.52, -.76, -.15, p=.009). FF significantly increased in all groups (Δ=0.10-0.11, p=.024-0.046); a significant decrease in T2*single was only seen in the PRP group (Δ=-8.07, -14.6, -1.55, p=.014). Conclusion Clinical improvement was evident irrespective of treatment but was greatest with PRP. SWS correlated with improvement in pain and may represent an adjunctive measure to assess healing in patellar tendinopathy. Correlative changes in T2* UTE quantitative markers suggest their potential for response assessment, but further research is needed to clarify their clinical applicability.